01 - Preheat oven to 300°F. Arrange four 6 oz ramekins in a deep baking dish.
02 - Combine persimmon pieces, 2 tablespoons sugar, and lemon juice in a blender. Process until completely smooth.
03 - Distribute persimmon puree evenly among ramekins, spreading into a thin layer at the bottom.
04 - Combine heavy cream and whole milk in a saucepan. Heat over medium heat until just steaming, avoiding boiling. Remove from heat.
05 - Whisk egg yolks, 1/4 cup sugar, vanilla extract, and sea salt in a mixing bowl until pale and slightly thickened.
06 - Gradually pour hot cream mixture into egg yolks while whisking continuously to prevent curdling.
07 - Pass custard through a fine mesh sieve into a pouring jug to remove any cooked bits.
08 - Gently pour strained custard over persimmon puree in each ramekin.
09 - Pour hot water into baking dish until it reaches halfway up the sides of the ramekins.
10 - Bake for 35 to 40 minutes until custards are just set but still slightly wobbly in the center.
11 - Remove ramekins from water bath. Cool to room temperature, then refrigerate for at least 2 hours or overnight.
12 - Sprinkle 1 teaspoon sugar evenly over each chilled custard. Use kitchen torch to caramelize until golden and crisp, or broil for 1 to 2 minutes.
13 - Let brûlée stand for 3 to 5 minutes to allow sugar crust to harden before serving.